Anxiety disorders are illnesses that can fill people's lives with overwhelming worry and fear. Types of anxiety disorders include panic disorder, obsessive-compulsive disorder, post-traumatic stress disorder, and agoraphobia. While each anxiety disorder has its own distinct features, they all have the common theme of excessive, irrational fear and dread. Often, the anxiety that a person feels is generally chronic, unremitting, and can grow progressively worse. Fortunately, treatments for anxiety can be effective at any age.